Address spec generator limitation translating handles in structs

[EwanC]

As part of PR #2666 I would like to define a UR entry-point that passed a list of structs, with each struct containing handles to UR objects. However the generated ur_ldrddi.cpp code only tranlsates the UR handles of the first struct in the list, which is a limitation in https://oneapi-src.github.io/unified-runtime/core/CONTRIB.html#limitations

This limitation is preventing UR command-buffer update from being able to take advantage of the OpenCL and Level-Zero APIs for update which let you pass a list of commands to update, currently we have to call UR update entry-point in a loop which is extra host overhead. Enabling passing a list of structs would allow more optimal native API usage.

[pbalcer]

@RossBrunton is currently working on removing the handle translation mechanism entirely in favor of a simpler approach that stores the loader metadata at the beginning of an adapter-allocated handle. See this PR. So this should go away on its own once that change goes in.

[RossBrunton]

I'm working on removing the handles, yes. However, it's looking like that could take longer than I'd like. I think it makes sense to hack this to work for now so that Ewan's work is unblocked, and then the hack should go away once the handle removal work is gone.

[kbenzie]

Closing this since we're working on removing the need for workarounds.